In recent years, the mainstream of mobile telephones has been the type in which two casings are foldably jointed by a joint part (mechanical joint parts such as hinge part, rotating part, and revolving part) since this type can be small in size, and protect its display screen and operation surface. Also, the type in which an external antenna and internal antenna are provided near the joint part of each casing has increased because this type allows foldable mobile telephones to be thinner and offers better usability.
A structural example of a conventional foldable mobile telephone will be described using drawings. Referring to FIG. 11, a mobile telephone 101 is made up by foldably jointing a first casing (refer to a first casing external surface 110) and a second casing (refer to a second casing external surface 120), and it comprises a first conductive part 111, a second conductive part 121, a joint part 130, a power supply (feeder) part 140 and an antenna 150.
The first conductive part 111 includes a conductive part (member) of components (circuit substrates, electronic parts, frames, etc.) housed in the first casing and a conductive part of the first casing in some cases, and as a whole, it can be considered to be a plate-shaped part disposed inside the first casing in terms of antenna characteristics. Likewise, the second conductive part 121 includes the conductive part of components (circuit substrates, electronic parts, frames, etc.) housed in the second casing and a conductive part of the second casing in some cases, and as a whole, it can be considered to be a plate-shaped part disposed inside the second casing in terms of antenna characteristics. The joint part 130 mechanically joints the first conductive part 111 and the second conductive part 121, and it becomes a pivotable part when the mobile telephone is folded. The power supply part 140 feeds power to the antenna 150, and is provided near the joint part 130 of the first conductive part 111 inside the first casing. The antenna 150 is led out from the area near the joint part 130 of the first conductive part 111 to the outside of the first casing (refer to the first casing external surface 110), and becomes an external antenna extended towards the second casing (refer to the second casing external surface 120) when the mobile telephone is opened. The antenna 150 is electrically connected to the power supply part 140, and operates as an antenna by being excited for oscillation between itself and the first conductive part 111. The tip of the antenna 150 is spiral shaped. When the mobile telephone 101 is opened, the extended part near the tip of the antenna 150 is at a position close to the second conductive part 121 and at a prescribed distance from the second casing external surface 120.
[Patent-Document 1]Japanese Patent Kokai Publication No. P2001-257522A[Patent-Document 2]Japanese Patent Kokai Publication No. P2001-156517A[Patent-Document 3]Japanese Patent Kokai Publication No. P2001-326524A[Patent-Document 4]Japanese Patent Kokai Publication No. P2003-179421A[Patent-Document 5]Japanese Patent Kokai Publication No. P2002-043826A[Patent-Document 6]Japanese Patent Kokai Publication No. P2002-344231A